Semiconductor power transistors and power rectifiers dissipate energy that causes a rise in temperature of the semiconductor device. This rise in temperature can adversely affect the operation of the device. Hence, it is desirable to remove this heat, to hereby prevent the device and the integrated circuit (IC) from overheating.
The art of heat exchange in semiconductor devices has provided for the use of natural diamond members to enhance the transfer of heat away from the semiconductor device.
For example U.S. Pat. No. 4,649,992 describes a diamond heatsink wherein a frusto-conical shaped diamond that is held on a high thermal conductivity mounting member by the use of a high thermal conductivity clamping member. The exposed top face of the diamond is lapped or polished, and a semiconductor device is mounted on this top face. U.S. Pat. No. 3,678,995 is generally similar in its teaching.
U.S. Pat. No. 4,698,901 describes a two terminal mesa semiconductor device having an integral heat sink of low thermal impedance. In this device, a completed mesa device is bonded to the metallized coating of a diamond heat sink which is in turn mounted on a gold stud.
U.S. Pat. No. 3,816,194 describes a high frequency diode having a diamond heat sink, the diamond heat sink layer being bonded to the current conducting junction by means of thermal compression. U.S. Pat. Nos. 3,872,496, 3,922,775 and 3,925,078 are generally similar in their teachings.
The publication IEEE Proceedings for the Seventh Biennial University/Government/Industry Microelectronic Symposium, Jun. 9-11, 1987, at pages 187-190 describes the fabrication of diamond electronic devices (Schottky diodes, PN junction diodes and NPN bipolar junction transistors) on a type IIb natural diamond chip by means of ion implantation. The publication also states that diamond or diamond-like thin films were grown from methane and other hydrocarbon gas sources by various ion beam and plasma assisted deposition methods.
The semiconductor art has also provided for the use of a fluid coolant. U.S. Pat. Nos. 4,712,609 and 4,730,665 are examples. In addition, U.S. Pat. No. 4,450,472 provides a semiconductor chip having microscopic size channels formed in the back side of the chip. A cover seals the chip's channel cavity area, and a coolant then flows therethrough with laminar flow. U.S. Pat. No. 4,631,636 teaches the use of cooling tubes in relation to circuit boards, and U.S. Pat. No. 4,697,205 teaches the use of a heat pipe relative to the cooling of a semiconductor substrate.
U.S. Pat. No. 4,765,400 provides a floating diamond plate that contacts the back surface of a semiconductor chip. The diamond plate communicates with pins that extend into a cavity through which a coolant flows.
As shown above, while the art recognizes the advantage of using natural diamond material in various configurations for cooling semiconductor devices, this end has been accomplished only by the use of relatively expensive bulk or natural diamond members or pieces which are of a limited planar size.
The need remains in the art to provide a method and an apparatus whereby a relatively inexpensive synthetic diamond, or diamond like, film may be deposited over the relatively large area of a semiconductor circuit chip or wafer, to thereby enable the high thermal conductivity of the diamond film to be utilized in cooling the chip or wafer.